1. Field of the Invention
The present invention relates to image processing. It relates more particularly to a method of detecting movement of an object and/or measuring the speed of the object relative to a matrix of pixels observing the scene within which the object is moving, the matrix being sensitive to radiation (for example light) emanating from the observed scene.
2. Description of the Prior Art
According to a known method of this kind, contrast vector information measured by a matrix of photosensors from a scene observed by the matrix is temporally encoded and the information measured by each photosensor is converted into a sinusoidal signal whose amplitude represents the magnitude of the local contrast vector and the phase represents the angle of the vector, and the detected maximum amplitude is compared to a decreasing ramp signal, a pulse being generated if the ramp signal is equal to the maximum amplitude The method further generates a second pulse if the sinusoidal function passes through zero after the first pulse is generated.
The times of occurrence of the two pulses generated in this way at each photosensor (referred to hereinafter as a pixel) constitute the time encoding of the information measured by the matrix of pixels
The sinusoidal function is the result of combining the information measured by a given pixel with that measured by the adjacent pixels in the matrix, modulated by the same sinusoidal function relative to time whose phase constitutes the weighting of the adjacent pixels in the combination.
Thus the method of the prior art determines the local contrast of the observed scene for each pixel of the matrix of pixels.
An object of the invention is to propose a method that is improved over the prior art previously described, in order to determine if there is relative movement between the matrix of pixels and an object moving in the observed scene, and, where necessary, to measure the speed of that movement.